test(load): reduce num of tables in errors loadtest

[taimoorzaeem]

The table not found error only generates hint when the total number of tables in a schema are less than 500.

Similar to #4839, this also should be updated.

postgrest-with-pg-18 -f test/load/errors.sql postgrest-run

curl -i localhost:3000/actoxs?actor=eq.1

HTTP/1.1 404 Not Found
Date: Sat, 25 Apr 2026 07:23:54 GMT
Server: postgrest/15 (pre-release)
Content-Type: application/json; charset=utf-8
Content-Length: 156
Proxy-Status: PostgREST; error=PGRST205

{
  "code":"PGRST205",
  "details":null,
  "hint":"Perhaps you meant the table 'test.actors'",
  "message":"Could not find the table 'test.actoxs' in the schema cache"
}

[wolfgangwalther]

Diff LGTM